The present invention is directed to a bone anchor for attaching tissue to bone, and to a device for deploying such an anchor in bone. More specifically, the invention is directed to a bone anchor which employs a “floating” washer that conforms to the angle of the bone surface to hold tissue in place, and to a deployment device having a plunger-like configuration that facilitates deployment of such an anchor.
Soft tissue, such as tendon, may become detached from a patient's bone as a result of injury or a medical procedure. In either case, the tissue must be re-attached in order to permit healing. Medical devices used to perform this function are known as bone anchors.
Traditionally, bone anchors were merely tacks or nails that were hammered through a patient's soft tissue and directly into the patient's bone. Anchors of this type, however, had many deficiencies. For example, they were prone to coming out of the bone, particularly in cases where patients were relatively active. In addition, because the anchors were hammered directly into the bone, deployment was difficult and could sometimes result in hairline fractures.
In recent times, more sophisticated bone anchors have been developed which alleviate some of the problems mentioned above. For example, many bone anchors now include prongs or something similar, which reduce the chances that the anchor will dislodge from the bone. Likewise, bone anchors have now been developed which can be inserted into pre-formed holes in bone, rather than being hammered.
When affixing tissue directly to bone, it is often desirable to deploy the bone anchor at an angle that is normal to the bone surface. If this is not done, then sufficient contact may not be achieved with the surrounding tissue to hold the tissue in place. Understandably, achieving such placement can be difficult when the anchors are placed endoscopically.
In addition to the foregoing, the force required to deploy a conventional bone anchor often makes deployment problematic. Driving a tack or nail-like anchor into bone, for example, is difficult if the surgeon does not have adequate leverage on the bone to counterbalance the force of impact.
Thus, there exists a need for a bone anchor which does not need to be deployed at a precise angle in order to attach tissue to bone reliably, and a device for deploying such an anchor which does not require a surgeon to impart substantial counterforce against the device during bone anchor deployment.
In view of the foregoing, an object of the invention is to provide improved bone anchors and methods for deployment thereof. A related object is to provide improved devices for deploying such anchors.
A further object is to provide anchors that attach tissue firmly and reliably, regardless of the angle of deployment.
A still further object is to provide anchors, methods and devices for deployment thereof suitable for use in endoscopic procedures.
Yet a still further object is to provide such anchors, methods and devices that can be deployed easily and without application of unnecessary leverage or counterforces.